When measuring noise figure with a noise meter, some factors need to be deducted to get accurate measurement results. The following are the main deduction items:
1. Noise background of the noise source
When measuring noise figure, the noise source needs to be used as a reference. The noise source itself will generate a certain amount of background noise, so this part of the noise needs to be deducted during measurement. Only in this way can the noise figure of the device under test be accurately measured.
2. Input noise in the gain method
In the measurement of the gain method, the gain of the amplifier needs to be accurately measured, and the amplified input noise is deducted from the output noise power so that the noise figure can be calculated.
3. Predetermined gain
In the measurement of the gain method, the gain of the DUT needs to be determined in advance. This is because the gain method calculates the noise figure by measuring the gain of the DUT and the absolute power of the output noise. If the gain of the DUT is not accurately determined, the measurement result will be affected.
4. Noise factor of spectrum analyzer
Spectrum analyzer will also introduce some noise during the measurement process. Therefore, when using spectrum analyzer to measure noise factor, it is necessary to consider the noise factor of spectrum analyzer and deduct it from the measurement result.
5. Other possible interferences
During the measurement process, it is also necessary to pay attention to other possible interferences, such as electromagnetic interference, power supply fluctuations, etc. These interferences may affect the measurement results, so corresponding measures need to be taken to suppress them.
Conclusion
When measuring noise factor with noise meter, it is necessary to deduct the background noise of the noise source, input noise, noise factor of spectrum analyzer and other possible interference factors to ensure the accuracy of the measurement results. Correct deduction is the key to obtaining reliable data.
